The invention relates to an analytical system for examining a body fluid, typically for blood sugar tests, with an exchangeable magazine as a consumable, which comprises a plurality of magazine units that are each provided with at least one analytical aid and with a transport element, a hand-held device having a magazine guide for receiving the magazine, and a transport mechanism that engages on the transport elements typically arranged in a ring shape, so as to transport the magazine in steps in the magazine guide. The invention further relates to a method for the operation of an analytical system.
In portable hand-held systems for automatic collection and measurement of body fluids, magazines with a plurality of disposable measurement units are increasingly being used in order to improve user friendliness. Compared to conventional measurement devices, these involve increased outlay in terms of mechanical movements. In an attempt to minimize the overall size of such systems, the structures of the magazine and of the device, which have to match each other, are becoming ever smaller, even though the tolerances of the individual parts do not decrease on the same scale. There are therefore ever greater demands on the positioning. The individual miniaturized tests require both a high level of precision and accuracy in terms of the position relative to the evaluation system and also a high degree of robustness in terms of the stability of the position during the measurement. The latter applies especially in the case of electrically evaluated tests, because each movement of contacts through which current flows leads to signal noises, and this disrupts the evaluation or makes it completely impossible. However, optical systems are also extremely sensitive to changes of position during ongoing measurement. A further aspect to be taken into account is that the magazine, as a consumable, should remain limited to the structures and components essential for the test procedure, so that the production costs can be kept as low as possible.
An analytical system of the type in question with a magazine in the form of a circular disk is mentioned in WO 2010/094426. It is proposed there that the analytical system can have a corresponding transport device which interacts with transport elements of the magazine in order to further transport the magazine units. Said document also discloses a method for producing such a magazine, to which reference is here made.
Generally speaking, concepts that involve accommodating an annular magazine over the ring center in the device, and leaving the precision of the movements to the device parts, lead to a very complex and expensive configuration since, in addition to the inevitable dimensional deviations of the magazine disk itself, many other structures of the device, which likewise necessarily have dimensional deviations and in some cases also a degree of running play, are included in the tolerance chain of the positioning. The six degrees of freedom of movement of the magazine can thus be brought under control only with an unjustifiable amount of effort.
Proceeding from this, an object of the invention is to further improve the systems and methods proposed in the prior art and to ensure precise positioning of the test units and magazine units, such that the requirements in terms of mechanics and measurement are satisfied even in the case of considerable miniaturization. At the same time, the magazine should be able to be exchanged and also transported by simple means.